Surgical approach of bentall procedure in a patient of pectus excavatum

A middle-aged man diagnosed case of Marfan syndrome associated with pectus excavatum presented with chest pain and dyspnea. Chest X-ray, transthoracic echocardiography and Computed tomography (CT) of heart and aorta revealed severe Aortic regurgitation with dilated aortic root, sinotubular junction and ascending aorta with normal size arch and descending aorta. Patient was taken for surgery. Pectus excavatum creates difficulties for heart exposure and cannulation for cardiopulmonary bypass. We planned for femoro-femoral bypass to carry out ahesiolysis and Bentall procedure without much difficulties. Postoperative stay of the patient was uneventful and followed up in regular interval

Confinement creates a 9 GPa ambience: emergence of cristobalite phases in a silica film

We present here the results of the x-ray fluorescence (XRF), x-ray photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive Analysis of x-rays (EDAX), x-ray Reflectivity (XRR), Secondary Ion Mass spectroscopy (SIMS) and x-ray Diffraction (XRD) studies of silica films spin-coated from a Tetraethyl Orthosilicate (TEOS) precursor on native and hydrophilized Al substrates. It is observed that the substrates are mainly porous (porosity similar to 33%) AlO(OH), there is a diffuse interlayer of highly porous (porosity similar to 90%) AlO(OH), essentially a modification of the substrate, and a top layer of silica composed of nanocrystals with in-plane dimensions of 100-300 nm and thickness of 2.5 nm with a sharply defined silica-hydrated alumina interface. The silica nanocrystals were found in the metastable high pressure cristobalite phases with the tetragonal or alpha-phase co-existing in its low (0.77 GPa) and high (9 GPa) pressure structures. This indicates a high normal stress developed from the confinement and provides a basis for the quantitative assessment of the confinement force, which comes out to be higher in value than the van der Waals force but weaker than the Hydrogen bonding force

Engineering robust cellulases for tailored lignocellulosic degradation cocktails

Lignocellulosic biomass is a most promising feedstock in the production of second-generation biofuels. Efficient degradation of lignocellulosic biomass requires a synergistic action of several cellulases and hemicellulases. Cellulases depolymerize cellulose, the main polymer of the lignocellulosic biomass, to its building blocks. The production of cellulase cocktails has been widely explored, however, there are still some main challenges that enzymes need to overcome in order to develop a sustainable production of bioethanol. The main challenges include low activity, product inhibition, and the need to perform fine-tuning of a cellulase cocktail for each type of biomass. Protein engineering and directed evolution are powerful technologies to improve enzyme properties such as increased activity, decreased product inhibition, increased thermal stability, improved performance in non-conventional media, and pH stability, which will lead to a production of more efficient cocktails. In this review, we focus on recent advances in cellulase cocktail production, its current challenges, protein engineering as an efficient strategy to engineer cellulases, and our view on future prospects in the generation of tailored cellulases for biofuel production. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Disulfide Bond Engineering of an Endoglucanase from Penicillium verruculosum to Improve Its Thermostability

Endoglucanases (EGLs) are important components of multienzyme cocktails used in the production of a wide variety of fine and bulk chemicals from lignocellulosic feedstocks. However, a low thermostability and the loss of catalytic performance of EGLs at industrially required temperatures limit their commercial applications. A structure-based disulfide bond (DSB) engineering was carried out in order to improve the thermostability of EGLII from Penicillium verruculosum. Based on in silico prediction, two improved enzyme variants, S127C-A165C (DSB2) and Y171C-L201C (DSB3), were obtained. Both engineered enzymes displayed a 15–21% increase in specific activity against carboxymethylcellulose and β-glucan compared to the wild-type EGLII (EGLII-wt). After incubation at 70 °C for 2 h, they retained 52–58% of their activity, while EGLII-wt retained only 38% of its activity. At 80 °C, the enzyme-engineered forms retained 15–22% of their activity after 2 h, whereas EGLII-wt was completely inactivated after the same incubation time. Molecular dynamics simulations revealed that the introduced DSB rigidified a global structure of DSB2 and DSB3 variants, thus enhancing their thermostability. In conclusion, this work provides an insight into DSB protein engineering as a potential rational design strategy that might be applicable for improving the stability of other enzymes for industrial applications

Enzyme stabilization in ionic liquids and at elevated temperatures

Enzymes are used in food processing, agriculture, animal nutrition, cosmetics, biofuels, pharmaceuticals, and the chemical industries. Enzymes designed by nature often do not function efficiently under required operation conditions such as elevated temperatures and the presence of ionic liquids (ILs) or organic solvents for the cost-effective production of chemicals and pharmaceuticals. Therefore, enzyme stabilization represents an essential and often obligatory step to utilize their catalytic functions under application conditions. In this respect, many protein engineering strategies have been successfully applied to tailor enzyme resistance towards ILs and elevated temperatures; however, derivation of general principles at the molecular level for efficient reengineering of enzymes are not well understood. A deeper molecular understanding of enzyme stability in ILs and at elevated temperatures can, therefore, facilitate efficient enzyme engineering. In this perspective, the main objectives of this thesis were to (i) elucidate the molecular interactions of Bacillus subtilis lipase A (BSLA) with ILs to improve the its stability in ILs and (ii) rational design thermostable variants, experimentally validate, and establish the structure-function relationship of the endoglucanase II (EGL-II) from Penicillium verruculosum. Molecular dynamics (MD) simulations were applied to study the interactions of BSLA and four commonly used imidazolium-based ILs (1-butyl-3-methylimidazolium (BMIM+) cation with Cl-, Br-, I-, and TfO- anions). Results showed that the overall conformation of the BSLA remained stable in the presence of BMIM+-based ILs (at concentrations ~10-19% v/v). The molecular distributions of IL ions revealed predominant surface interactions of BMIM+ cations on the BSLA surface through hydrophobic and π-π interactions. The reduction of the BSLA activity in the presence of ILs was mainly attributed to dominant surface interactions of BMIM+ cations that strip off essential water molecules from the BSLA surface. To this end, the comparison of MD simulations results with experimental results from the full site saturation mutagenesis BSLA library (comprising the positional full natural amino acid diversity termed BSLA-SSM library) showed that most of the beneficial positions contributing to the improvement in resistance are located in the BMIM+ binding regions. Subsequently, a comprehensive analysis of the BSLA-SSM library indicated that resistance of the BSLA in ILs could be achieved through introduction of both positive and negative charged surface residue substitutions. In order to understand the molecular basis of these experimental findings, MD simulations were performed to understand the effects of these introduced charged residues to improve the resistance of the BSLA in [BMIM][Cl]. It was found that introduction of positive and negative charged residues showed an opposite electrostatic effect towards BMIM+ cations and Cl- anions, respectively. The BMIM+ cations showed predominant surface interactions with the wild type BSLA and its variants compared with Cl- anions. The beneficial effects of substitutions to charged residues in improving the resistance of the BSLA are mainly attributed to the recovery of essential water molecules in the solvation shell of the substitution sites. These findings revealed that reducing BMIM+ binding and retaining the essential water molecules through surface charge engineering might improve the resistance of the BSLA and most likely structurally similar α/β-hydrolases in ILs. Lignocellulosic biomass is one of the most available and renewable resources in the bioeconomy. EGL-II is one of the essential enzymes in the multi-cellulases cocktails that synergistically hydrolyze lignocellulose. However, thermostability is a major issue of the EGL-II application for efficient lignocellulose hydrolysis under industrially required elevated temperatures. In this study, two rational strategies were applied to design thermostable variants, experimentally validate, and establish the structure-function relationship of the thermostable variants of EGL-II from P. verruculosum. Firstly, structure-guided disulfide bonds (DSBs) engineering was employed, and two variants S127C-A165C (DSB2) and Y171C-L201C (DSB3) were identified. These variants displayed a 15-21% increase in specific activity against carboxymethylcellulose (CMC) and β-glucan compared to the wild type EGL-II. After incubation at 70 °C for 2 hours, the DSB variants retained 52-58% of their activity toward both substrates, while the wild type EGL-II retained only 38% of its activity. At 80 °C, the DSB2 and DSB3 variants retained 15-22% of their activity after 2 hours, whereas the wild type EGL-II was completely inactivated after the same incubation time. Further, MD simulations revealed that the introduced DSBs rigidified the overall structure of the variants and thereby enhanced their thermostability. Secondly, sequence and structure-based strategies were employed to study the effect of the introduction of proline residues, and five variants were identified, including E34P, L75P, T115P, S256P, and S308P. These variants were screened for thermostability using barley β-glucan substrate at different temperatures ranging from 50-95 °C. Out of these variants, the most stabilizing variant S308P showed a 4- and 2.4-fold increase in half-life time (t1/2) at 70 °C and 80 °C compared to the wild type EGL-II, while maintaining the specific activity. Subsequently, MD simulations revealed that S308P stabilized the C-terminal region by inducing a conformational change (I301-Y313) in the neighboring residue I309 that forms a new H-bond with E263 of the nearby α-helix. These results provide that DSBs and proline engineering are an effective and useful approach for improving the thermostability of the EGL-II and most likely structurally similar (α/β)8 barrel hydrolases. In conclusion, this thesis advanced the knowledge to improve the resistance of the BSLA in ILs and thermostability of EGL-II. In the first part, the molecular understanding of imidazolium-based ILs interactions with the BSLA and its charged residue substitutions open the way to surface charge engineering through the introduction of positively charged residues that could simultaneously retain essential water molecules and prevent the interaction of ILs ions, and thereby enhance resistant/stability of the BSLA and structurally similar α/β-hydrolases in ILs. In the second part, DSBs and proline engineering represent efficient approaches for tailoring thermostability of the EGL-II, which could generally be applicable for structurally similar (α/β)8 barrel hydrolases. Computer-assisted DSBs and proline engineering are efficient enzyme engineering strategy alternatives to pure experimental approaches, the latter being costly and time-consuming for the engineering of the enzyme stability. Taken together, DSBs and proline engineering are effective approaches for thermostability engineering of EGL-II and structurally similar (α/β)8 barrel hydrolases, which are highly essential for enzymatic lignocellulosic biomass degradation for the sustainable production of value-added chemicals and biofuels. Besides, these results open the way for systematically analyzing the effectiveness and additivity of DSBs and proline engineering for stabilization of enzymes in such unnatural conditions broadening their potential use in biotechnological applications

Rationalization of supramolecular interactions of a newly synthesized binuclear Cu(II) complex derived from 4,4′,6,6′-tetramethyl 2,2′-bipyrimidine ligand through Hirshfeld surface analysis

A new binuclear copper (II) complex [Cu2L2Cl4(H2O)2] (1) derived from 4,4',6,6'-tetramethyl-2,2'-bipyrimidine (L) has been synthesized and characterized by the single crystal X-ray diffraction method. Single crystal analysis of complex 1 reveals that it crystallizes in the space group P21/n under a monoclinic system (β = 97.995(2)°, a = 7.6483(2), b = 7.2158(3) and c = 17.8477(6) Å). The ligand acts as a bis-bidentate one and each copper (II) center bears a square pyramidal geometry exploiting N2Cl2O chromophore. In the solid state, the complex is stabilized through classical O-H···Cl intermolecular hydrogen bonding incorporating coordinated water (as a solvent) and chloride ions and lone pair···π interactions. The Hirshfeld surface analysis demonstrates H···H/H···H, H···Cl/Cl···H, H···C/C···H, and C···Cl/Cl···C intermolecular interactions as the major contributor interactions in the solid-state packing of the molecular crystal. Interaction energy calculations carried out employing the wavefunction generated via B3LYP/6-31G(d,p) highlight the dominance of electrostatic energy and the contribution of polarization and dispersion energy towards the total energy of complex 1 in the solid state

Root fracture resistance test of cast post using seat and non-seat preparation design in central maxillary incisor

Post-placement is one of the treatment plans supporting the success of a restoration. The design of root canal preparation is a factor in the success of post-use. The purpose of this study was to investigate the root fracture resistance of the root canal preparation for cast post with a seat and non-seat preparation. The study was a laboratory experimental study using 20 upper central incisors that met the criteria in the study. Ten incisors were prepared using seat design while the other ten were prepared using non-seat design. Then tested the compressive test by Universal Testing Machine with test speed 0,5 mm/min. The results of the fracture strength were analyzed using t student statistical test. The analysis showed a significant difference between the non-seat group and the seat group (α=0.05). The average force in the non-seat group was 852.27 N with a standard deviation of 112.6 N while the seat group showed a value of 495.78 N and 82.90 N, respectively. It was concluded therefore that the root fracture resistance in the non-seat root canal preparation design was higher than the seat preparation design

Cytological diagnosis of adamantinoma of long bone in a 78-year-old man

A clinicohistopathological study of a rare case of adamantinoma of long bone in a 78-year-old patient is presented. The cytological features when evaluated in conjunction with clinical and radiologic features are sufficiently diagnostic. The primary knowledge of its existence and knowledge of its cytological features are important for a correct preoperative cytological diagnosis